Butyrylcholinesterase is an enzyme found mainly in plasma. Although the normal physiological role of butyrylcholinesterase is unknown, butyrylcholinesterase has been shown to metabolize acetylcholine, degrade cocaine, and inactivate anaesthetic drugs and muscle relaxants, including succinylcholine, succinylcholine-like compounds and mivacurium (Gorelick et al., Drug Alcohol Depend., 48(3): 159-65, 1997; Stewart et al., Clin. Pharmacol. Ther., 25: 464-8, 1979; Krasowski et al., Can. J. Anaesth., 44:525-34, 1997; Jatlow et al., Anesth. Anag., 58:235-8, 1979). Butyrylcholinesterase has also been shown to act as an antidote to nerve gas and organo-phosphorus compounds (Ashani et al., Biochem. Pharmacol., 41:37-41, 1991; Broomfield et al., JPET, 259:633-8, 1991; Doctor et al., New Approaches to Medical Protection Against Chemical Warfare Nerve Agents In Chemical Warfare Agents: Toxicity at Low Levels, pp. 191-214, Lewis Publishers, Inc., 2001; Ashani et al., Drug Development Research, 50:298-308, 2000).
Previous methods for isolating butyrylcholinesterase involved either ammonium sulfate precipitations or electrophoresis, which resulted in yields of butyrylcholinesterase of about 10% and purities of 10% or less (Goedde et al., Humangenetik., 1:311-8 1965; Haupt et al., Blut., 14(2):65-75, 1966). Present methods employing chromatography of plasma result in yields of butyrylcholinesterase ranging from 30-40% to 63% (Grunwald et al., J. Biochem. Biophys. Methods, 34(2):123-35, 1997; Lockridge et al., J. Biol. Chem., 287:12012-8, 1982). In order to evaluate butyrylcholinesterase for its therapeutic and pharmacological properties, large quantities of purified, virally inactivated butyrylcholinesterase are needed.
Within the art, there remains a need for a method whereby large quantities of virally inactivated butyrylcholinesterase can be isolated from biological fluids such as plasma in a highly purified form. Until now, there have been no commercially viable, easily performed methods to efficiently and economically produce large quantities of purified, virally inactivated butyrylcholinesterase from biological fluids. The methods of the present invention address that need.